There is an ongoing concern in the tobacco industry to produce cigarettes having wrappers which reduce the ignition proclivity of the smoking article, or the tendency of the smoking article to ignite surfaces which come into contact with the lit smoking article. Reports have been made of fires attributed to burning cigarettes coming into contact with combustible materials. A justifiable interest exists in the industry to reduce the tendency of cigarettes, or other smoking articles to ignite surfaces and materials used in furniture, bedding, and the like upon contact.
Thus, a desirable feature of smoking articles, particularly cigarettes, is that they self-extinguish upon being dropped or left in a free burning state on combustible materials.
It has long been recognized in the tobacco industry that the cigarette wrapper has a significant influence on the smolder characteristics of the cigarette. In this regard, various attempts have been made in the art to alter or modify the cigarette wrappers in order to achieve the desired tendency of the cigarette to self-extinguish, or in other words to reduce the ignition proclivity characteristics of cigarettes.
The prior art describes the application of film-forming solutions to cigarette paper to reduce the paper permeability and control the burn rate. It has been shown that when these materials have been applied in discrete areas along the length of the cigarette, the cigarette shows a reduced propensity to ignite a substrate, tends to self-extinguish, and has a higher puff count.
U.S. Pat. No. 5,878,753 to Peterson and U.S. Pat. No. 5,820,998 to Hotaling, et al. which are incorporated herein by reference, for example, describe a smoking article wrapper being treated with a film-forming aqueous solution to reduce permeability. U.S. Pat. No. 5,878,754 to Peterson which is also incorporated herein by reference describes a smoking article wrapper being treated with a non-aqueous solution of a solvent soluble polymer dissolved in a non-aqueous solution to reduce permeability.
Although many improvements have been made in the art, there is still a need for an improved method for producing a cigarette wrapper with reduced ignition proclivity properties. For example, problems have been experienced in producing a smoking article that self extinguishes when left burning on an adjacent surface but does not self extinguish when left in a free air burning state, such as when a cigarette is being held and not puffed or when a cigarette is propped in a ashtray. Specifically, problems have arisen in designing smoking articles as described above on a repetitive basis.
Another problem that has been experienced in designing smoking articles with reduced ignition proclivity characteristics is that the treated areas on the smoking articles have a tendency to adversely affect the taste and enjoyment of the article. For example, typically the smoking articles include a paper wrapper having treated areas separated by untreated areas. The smoke components and the taste of the article has a tendency to change as a burning coal advancing along the article advances from an untreated area to a treated area.
Likewise, problems have also been experienced in controlling the ash properties of the smoking articles. In general, a white and cohesive ash is desired. The ash characteristics, however, have a tendency to change as the burning coal advances from an untreated area to a treated area. A need currently exists for a paper wrapper that not only reduces the ignition proclivity characteristics of a smoking article but also does so without substantially affecting the ash characteristics of the article.